Home | About | Sematext search-lucene.com search-hadoop.com
 Search Hadoop and all its subprojects:

Switch to Plain View
Hive >> mail # user >> Map side join


+
Souvik Banerjee 2012-12-07, 19:58
+
bejoy_ks@... 2012-12-07, 20:10
Copy link to this message
-
Re: Map side join
Hi Bejoy,

That's wonderful. Thanks for your reply.
What I was wondering if HIVE can do map side join with more than one
condition on JOIN clause.
I'll simply try it out and post the result.

Thanks once again.

Regards,
Souvik.

On Fri, Dec 7, 2012 at 2:10 PM, <[EMAIL PROTECTED]> wrote:

> **
> Hi Souvik
>
> In earlier versions of hive you had to give the map join hint. But in
> later versions just set hive.auto.convert.join = true;
> Hive automatically selects the smaller table. It is better to give the
> smaller table as the first one in join.
>
> You can use a map join if you are joining a small table with a large one,
> in terms of data size. By small, better to have the smaller table size in
> range of MBs.
> Regards
> Bejoy KS
>
> Sent from remote device, Please excuse typos
> ------------------------------
> *From: *Souvik Banerjee <[EMAIL PROTECTED]>
> *Date: *Fri, 7 Dec 2012 13:58:25 -0600
> *To: *<[EMAIL PROTECTED]>
> *ReplyTo: *[EMAIL PROTECTED]
> *Subject: *Map side join
>
> Hello everybody,
>
> I have got a question. I didn't came across any post which says somethign
> about this.
> I have got two tables. Lets say A and B.
> I want to join A & B in HIVE. I am currently using HIVE 0.9 version.
> The join would be on few columns. like on (A.id1 = B.id1) AND (A.id2 > B.id2) AND (A.id3 = B.id3)
>
> Can I ask HIVE to use map side join in this scenario? Should I give a hint
> to HIVE by saying /*+mapjoin(B)*/
>
> Get back to me if you want any more information in this regard.
>
> Thanks and regards,
> Souvik.
>
+
Souvik Banerjee 2012-12-11, 23:12
+
bejoy_ks@... 2012-12-12, 14:04
+
Souvik Banerjee 2012-12-12, 20:27
+
bejoy_ks@... 2012-12-13, 17:12
+
Souvik Banerjee 2012-12-13, 18:00
+
bejoy_ks@... 2012-12-13, 18:06
+
Souvik Banerjee 2012-12-13, 18:36
+
Souvik Banerjee 2012-12-27, 23:05